A series of tetrakis(4-hydroxyphenyl)pentanes and tetrakis(4-hydroxyphenyl)-p-xylenes having relatively high molecular weights (550−810) were prepared and evaluated as antioxidants for tetralin at 60 °C by means of an oxygen-absorption method. Introduction of alkyl groups to the ortho positions of the phenolic hydroxyl group was shown to improve antioxidant activities for both series of compounds.